<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .box1 {
            position: relative;
            width: 500px;
            height: 500px;
            /* z-index: 1; */
            background-color: pink;
        }

        .box2 {
            position: absolute;
            top: 0;
            /* z-index: ; */
            /* visibility: hidden; */
            display: none;
            width: 1000px;
            height: 1000px;
            background-color: skyblue;
        }

        .box1:hover+.box2 {
            display: block;
            /* visibility: visible; */
        }
    </style>
</head>

<body>
    <div class="box">
        <div class="box1"></div>
        <div class="box2"></div>
    </div>
</body>

</html>